Earth’s Dynamic Systems: Ecosystems and Tectonics
Ecosystems
An ecosystem is a natural system in which the life cycles of flora and fauna are closely related to each other.
Non-Living Environment
The non-living environment includes:
- Water
- Air
- Solar energy
- Rocks
- Soils
Living Environment
The living environment includes:
- Plants
- Animals
- Insects
- Microorganisms
- People
Energy Flow
Each ecosystem is sustained by the flow of energy through it. The main source of energy is sunlight, which is absorbed by green plants and converted through the process of photosynthesis.
Nutrient Recycling
Some nutrients are continually circulated within the ecosystem and so are part of a closed system. This consists of plants taking nutrients from the soil.
Ecosystem Energy and Nutrient Flow:
Non-Living Environment (solar energy) → Producers (photosynthesis) → Consumers (herbivores eat green plants) → Consumers (carnivores eat herbivores) → Decomposers (bacteria break down dead matter)
Tropical Rainforests
Tropical rainforests grow in places that have an equatorial climate. They represent one of the richest vegetation systems in the world, but the trees have to adapt to high temperatures and a year-round growing season. The trees are deciduous, and the vegetation grows in distinct layers. Trees must grow rapidly to reach the life-giving sunlight. Lianas are plants that are vines. During the wetter months, large areas of land near the main rivers are flooded. There are approximately 1,000 species of trees.
Tropical Rainforest Nutrient Cycle:
Numerous Fallen Leaves → Leaves Decay Rapidly to Form Humus → Nutrients are Added to the Soil → Rich Soil → Rich Tree Growth
Tropical Savanna Grasslands
The vegetation in tropical savanna grasslands is dense woodland with tall grass patches.
The Dry Season
During the dry season, scattered deciduous trees lose their leaves, turn yellow, and become dry. Most of the plants are drought-resistant.
The Wet Season
With the first rains, grass seeds germinate, and trees produce new leaves. Under hot, wet conditions, the grasses grow quickly. The vegetation of these areas has been significantly altered due to fire.
Mediterranean Vegetation
Mediterranean vegetation consists of woodland and scrub. Evergreen oaks and conifers dominate this vegetation. In Europe, two types of scrub exist: the maquis and the garigue. The vegetation sometimes has a protective bark, a short life cycle, and long tap roots. Mediterranean vegetation has been seriously affected by:
- Deforestation: Trees are burned on purpose to create space for buildings and construction.
- Grazing Animals: Sheep and goats eat the leaves of young trees.
- Fire: Frequent forest fires.
Coniferous Forests
Coniferous forest vegetation is full of spruce and other coniferous trees. Coniferous trees are softwoods, used for paper and pulp production.
Plate Tectonics & Tectonic Activity
Earthquakes and volcanic eruptions are caused by movements inside the Earth. They cannot be precisely predicted. There are about a thousand Earth movements each year.
Earthquakes
Earthquake activity is frequent in regions such as Alaska, India, or the Philippines.
Volcanoes
Volcanic activity is frequent in areas like Mount St. Helens or Krakatoa.
Constructive Margins
Constructive margins occur where two plates move away from each other. Submarine explosions accompanied by ejections of steam and ash gave birth to islands like Surtsey.
Destructive Margins
Destructive margins occur where plates consisting of oceanic crust move towards plates of continental crust. The oceanic crust is subducting towards the continental crust.
Conservative Margins
Conservative margins are found where two plates slide past one another. The crust is neither formed nor destroyed, and there is no volcanic activity. For example, the continental crust moves slowly against the Pacific Plate.
Collision Margins
Collision margins occur where two plates consisting of continental crust move together. The rocks between them are forced upwards, forming mountain ranges. The continental crust cannot be subducted or destroyed.